Method and apparatus for generating steam



M. H. KUHNER METHOD AND APPARATUS FOR GENERATING STEAM June 19, 1934.

Filed July 29, 1932 2 Sheets-Sheet 1 1 INVENTOR MAX H. KUHNER BY WATTORNEY June 19, 1934. M, H, KUHNER 1,963,524

METHOD AND APPARATUS FOR GENERATING STEAM Filed July 29. 1932 2Sheets-Sheet 2 F l6 2 LW MAX H. KUHNER A TTORNEY Patented June 19, 1934METHOD AND ArPARA'rUs Fort GENERATING STEAM Max lL'Kuhner, Worcester,Mass, assignor to Riley Stoker Corporation, Worcester, Mass, acorporation of Massachusetts Application July .29, 1932, Serial No.626,09

3 Claims.

- This invention relates to a method and apparatus for generating steamand controlling the temperature of superheated steam, and more par--'ticularly to the generation of steam at two differ- 25 cut pressuresand temperatures.

In many industrial steam generating plants there is a demand for steamat different pressures andtemperatures. High pressure high temperaturesteam is required for the production of power in steam turbines orengines, and low pressure loW temperature steam is needed in connectionwith various manufacturing processes. .For economical reasons it isundesirable to provide two separate boilers to operate at'differentpressures, and l 18 various prior constructionshave accordingly beenproposed to provide the required .steam supplies froma single boiler.These prior arrangements have, however, been complicated, expensive,bulky, and subjectto various difficulties in'actual operation.

.It is accordingly-the main object of the inventiontoprovide a simpleand inexpensive method of. producing steam at two different pressuresand temperatures, together with a compact and reliable apparatus forcarrying on the said method of steam-production.

;It is a furtherobject of the invention toprovide 'a simple and reliablemethod and apparatusfor accurately controlling the temperature ofsuperheated steam. 7

With these and other objects in view, as will be "apparent tothoseskilled in the art, the invention resides in the combination ofparts and the steps of the process set forth in the specification and a,covered by theclaims appended hereto.

-Referring to the drawings illustrating one em- 'ly needed at a lowertemperature and .pressure. Moreover, there is usually no definiterelation- I bodiment of the invention, and in which like referencenumerals indicate like parts,

Fig. 1 is a longitudinal section through a steam the line 1-1 of Fig. 2;

Fig. 2 is an enlarged 2-2 of Fig. l;;and

Fig. 3 is a section on the line 3-3of Fig. 2.

section taken on the line ,In the drawings I have illustrated a watertube boiler of the well-known Badenhausen type, com- ..prising a muddrum 10, a waterdrumll, and a steam and water drum 12. Drums 10 and 11are connectedby an upwardly and forwardly sloping 4150 bank of tubes 14,and drums 11 and 12 are con- 7 .hot gases from the ever require steamgenerating apparatus, the section being taken on and the interposedbanks of tubes. A furnace or combustion chamber 18 is located beneaththe tube bank 14, the rear wall 19 oi the chamber being beneath the muddrum 10, and the front wall 20 of the chamber being adjacent to thewater drum 11.

A steam drum-22 is mounted above the water drum l1, and a row ofsubstantially horizontal tubes 23 leads from the steam and water drum 12to the steam drum. The tubes 23 support refrac- 1 tory material Zi'WhlChforms a roof for the boiler.

The tubes of t e first tube bank 4 r ben upwardly intermediate theirlengths to provide a space for a superheater 26 therebeneath. The inletends of the superheater tubes are connected j'to the steam drum 22,and'their outlet'ends are connected to a horizontal header 2'] locatedabove the roof '24. vA row of water tubes 28 extends between the drums10 and 11 below the superheater, toprotect the superheater tubes to someextent 57 -5 from the radiant heat, of the furnace.

Baflies 29 of refractory material are arranged todireot the furnace overthe superheater 26 and the tube banks l4, l5 and 16 in the order namedto a gas outlet 30. It will be apparent that all the steam generatedinthe boiler willbe ,de-

livered to the steam and water drum l2, and from this drum it will flowthrough the tubes 23110 the steam drum 22, and thence through thesuperoheater 26 to the header 27.

.185 5, In passing through the .superheater, the steam will be raised toa high temperature and hence will besuitable for use in a steamturbinefor-the Many industrial plantshowfor process work as well as 0 powergeneration, and the process steamis usualgeneration of power.

ship between the quantities required for the two purposes, andthesequantitiesmay vary entirely independently throughout the day.

preferably accomplished by desuperheating aportion only of the steam forprocess, and controlling this portion in, relation to the total quantityM 5 process steam to provide the desired result.

In the preferred construction illustrated I have provided adesuperheater comprising an inlet header 32 and an outlet header 33connected by a group of tubes 34. Key caps 36 are provided in 110 theheaders for convenience in expanding the tube ends. This desuperheateris shown mounted in the boiler drum 12, but it will be apparent that itcan be mounted in any drum which contains a supply of water. The drum 12is provided with the usual manholes 37, through which the parts of thedesuperheater may be inserted to be assembled inside the drum. Themanholes 3'? are of course normally closed by cover plates (not shown).The headers 32 and 33 are preferably vertical, and the tubes 34 arelocated in the lower part of the drum below the water level. The upperends of the headers 32 and 33 are connected by flanged joints to weldingnecks 39 and 40 respectively, which are welded to the lower ends ofwelding necks 41 and 42 respectively. These fittings 41 and 42 areexpanded and welded to the upper wall of the drum 12. The usual safetyvalve 44 is mounted on the drum, and connections 45 are provided for theusual water column.

A cross fitting 4'7 is mounted on the welding neck 41, and a pipe 48leads from the superheater outlet header 27 to one lateral branch of thecross. The upper branch of the cross is connected to a pipe 49 which maylead to a steam turbine or other apparatus for using high pressure hightemperature steam. The welding neck 42 at the outlet of thedesuperheater 34 is connected to a delivery pipe 51 leading to apparatusrequiring low pressure low temperature steam, and this pipe is pro--vided with a valve 52. A by-pass pipe 53 leads from the cross 47 to thepipe 51 and preferably connects with said pipe at a point beyond thevalve 52. The by-pass pipe is provided with a valve 55 and an expansionloop 56.

It will now be apparent that the pressure and temperature of the steamin the pipe 51 will depend upon the adjustment of the valves 52 and 55.Both of these valves are preferably of the wellknown diaphragm-operatedtype, one being actuated in accordance with the pressure in pipe 51 andthe other in accordance with the temperature in pipe 51. In theembodiment illustrated, valve 52 is pressure actuated, being connectedto pipe 51 by a small control pipe 58, and valve 55 is temperatureactuated, being connected by a small tube 59 to a temperature responsivebulb 60 located in the pipe 51.

The operation of the invention will now be clear from the abovedisclosure. Hot gases from the furnace 18 pass through the boiler andgenerate steam at a comparatively high pressure, all of which flowsthrough the superheater 26 and is raised to a high temperature. Thesuperheated steam flows through the header 27 and pipe 48 to the cross47, and a part of this steam flows through the pipe 49 to a turbine orother apparatus. The remainder of the steam divides, a portion flowingthrough the desuperheater 34 and a portion through the by-pass pipe 53.The steam which passes through the desuperheater is reduced intemperature by the transfer of heat to the water in the drum 12. Thisheat is of course not wasted, but aids in the generation of steam. Thevalves 52 and 55 function automatically to maintain the desired steamconditions in the pipe 51 leading to the process steam consumingapparatus. If the pressure in pipe 51 increases, valve 52 will closeslightly to reduce the steam flow and restore the desired pressure. Ifthe temperature in pipe 51 increases, valve 55 will close slightly toreduce the flow of high temperature steam through the by-pass pipe 53and thus restore the desired temperature. The valves 52 and 55 thuscooperate in controlling both the total steam flow to the delivery pipeand the relative rates of flow in the desuperheater and by-pass.

Since there is a substantial pressure drop through both the valves, theycan be of comparatively small size, and hence are relativelyinexpensive. The pressure in the drum 12 is but slightly in excess ofthat within the desuperheater, so that the tubes 34 and headers 32 and33 can be of light construction. The desuperheater takes up no space inthe boiler room, and can readily be disconnected from the welding necks39 and 40 and pushed to one side in case the boiler tubes are to becleaned. All the steam generated in the boiler passes through thesuperheater, so that the superheater is protected from overheating eventhough the turbine is shut down and all the steam is used for processwork. The desired pressure and temperature for the process steam will bemaintained constant irrespective of the relative quantities of steamused for power 01' process, and regardless of any variation in thetemperature or pressure of the steam delivered by the superheater.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. Steam generating apparatus comprising a boiler, a superheaterarranged to receive steam from the boiler, a desuperheater arranged toreceive steam from the superheater, a delivery pipe arranged to receivesteam from the desuperheater, a valve in the delivery pipe, a by-passpipe for the desuperheater arranged to discharge superheated steam intothe delivery pipe at a point beyond the valve, a valve in the by-passpipe, means to actuate one of said valves in accordance with thesteampressure in the delivery pipe, and means to actuate the other ofsaid valves in accordance with the steam temperature in the deliverypipe.

2. Steam generating apparatus comprising a boiler, a superheaterarranged to receive steam from the boiler, a desuperheater arranged toreceive steam from the superheater, a delivery pipe arranged to receivesteam from the desuperheater, a valve in the delivery pipe, means toactuate said valve in accordance with the steam pressure in the deliverypipe, a by-pass pipe for the desuperheater arranged to dischargesuperheated steam into the delivery pipe at a point beyond the valve, avalve in the by-pass pipe, and means to actuate the last mentioned valvein accordance with the steam temperature in the delivery pipe. I

3. The method of operating a desuperheater having a by-pass comprisingthe steps of supplying superheated steam at a comparatively hightemperature and pressure to the desuperheater and by-pass, mixing thedesuperheated steam with the superheated steam flowing through the bypass, controlling the rate of flow through the desuperheater to providea substantially constant reduced pressure in the mixture, andcontrolling the rate of flow through the by-pass to provide asubstantially constant reduced temperature in the mixture.

MAX H. KUHNER.

